Non-removable screw



y 26, 1954 J. K. BARRY NON-REMOVABLE SCREW Filed Oct. 9, 1961 FIG. 3

INVENTOR. Jb/iil )Z'Barzy,

1816'; B BB 30 32 FIG-3'; 1 a0 j 3,134,291 i i NON-REMOVABLE SCREW John K. Barry, Springfield, Pa., assignor to South Chester Corporation, Lester, P'a., a corporation of Delaware Filed ct. 9, 1961, Ser. No. 143,953

2 Claims. (Cl. 85-45) I ,This invention relates generally to nonremovable screws, and particularly to a type of nonremovable screw used to permanently fasten together parts to prevent disconnection thereof by unauthorized persons. 1

A principal object of the invention is to provide a.

screw which not only may be used to prevent such tampering as may be attempted by honest people, with a knife, coin, etc., as whensouvenir hunting, butwhichalso may be used in the, construction of jails, institutions for mental cases, safes, etc. J 7

.Another object is to provide such a screw with a head that cannot be sawed, chiseled, and drilled toform a slot or hole to receive a tool for removingthe screw.

, Another object is to provide such a screw which may be'installed quickly and at minimum cost, and which, when installed, presents a smooth, attractive head without any necessity for a grinding or any other secondary operation. H e

Other objects ofthe invention will'become apparent whenthe" following description is read with reference to the accompaying drawing, in which: I

' FIG. 1 is a section through a punch. press, showing the press about to close on a flattened button head screw;

FIG. 2 is'similar to FIG. 1, but shows the condition of parts after the punching operation; 7

J'- FIG. 3 is a perspective viewpf the fully formed screw;

FIG. 4 isa perspectiveview looking atthe lower end of a tool used til-apply thescrewj v FIG. 5 is a section'showing the tool applying the screw tothe work; t

FIG. 6 is similar to FIG. 5, but shows the final stage in the application of the screw to the work; I 7 FIG. 7 is a perspective view showing the screw applied tothework; M 1

FIG. 8 is a section through a punchpress showing the press. about to close on a countersunk head. screw; FIG. 2 is similar to'FIG. 8, but shows the condition of partsfaf ter the" punching operation; l

FIG. 10 is a perspective view'of the fully formed screw shown in FI G@9; V

FIG. v1'1 is a perspective'vicw looking at the lower end of a tool used to apply the countersunk head screw;

FIG. 12 is a section showing the tool applying the countersunk head screw to the work;

FIG. 13 is similar to FIG. 12, but shows the final stage in the application of the countersunk head screw to the work; *and e -FIG.14 is a perspective view showing the countersunk head screw applied to the work.

Referring particularly to FIG. 3, a nonremovable I punch bars 28 having square cut working ends.

formed in conventional manner. mounted upon the bed 24 of the punch press by inserting 3,134,291 Patented May 26,, 1964 drical opening 26, and on diametrically opposite sides of the opening 26 respectively are a pair of axially shiftable The head of the punch press, generally designated 30, is provided with a cavity 32 in the base of which are formed a pair of diametrically opposite cylindrical depressions '34. In the manufacture of the'screw, the threaded shank 10 and a plain flattened button head, designated 36, are 3 Then the screw is its shank 10 in the opening 26, whereupon the plain head 36 of the screw seats uponthe upper surface of the bed 24. Now the head 30 of the punch press is lowered through the position shown in FIG. 1 to that of FIG. 2. The plain head 36 nests snugly in the cavity 32, and the depressions 34. are aligned respectively with the punch bars 28. When the punch bars are actuated,

they punch-shear from the plain head 36 the pins 22, leaving in the head 36 .the openings20. The lower end portions of the pins 22 remain in the openings 20 while the upper end portions of the pins 22 are projected into the depressions 34 in the base of the cavity 32, as

shown.)

A Referring particularly to FIGS. 4, 5, and 6, a tool for applying the sgrew is generally designated 38, The tool comprises a main body 40,.the lower end of which is pro- 2 vided with a cavity .42 and a pair of diametrically opn which is to be secured together by the screw comprises; for, example, mutually overlying plates 48 and 50. The

positedepressions 44, and the upper end of which is provided with a handle 46.

Referring particularly to FIGS. .5, 6, and 7, the work work is provided with a tapped opening 52. The shank 10 of the screw isthreaded into'the opening 52.until the undersurface 14 of the head"12 engages the plate 50,

. whereupon the lower end of the tool 38 is' applied to r 12 ofthe screw, as shown in FIG. '6.

' the. head-.12, as shown in FIG. 5. The head 12 nests f-erring particularly to FIG. 7, it will be noted thatthe upper end surfaces of pins. 22 are flushand merge smoothly with the upper surface 16 of the screw head 12.

Referring now particularly to FIG. 10, a modified form of the non-removable screw comprises a threaded shank 'and a head, generally designated 62, having an axially .55 tapered undersurface 64, a flat top surface 66, and a cylindrical peripheral edge 68. 1

Formed in the head 62 are a pair of axially extending diametrically opposite cylindrical through openings 70,

screw constructed in. accordance with the invention com-' "the upperiportion of its opening 20, and the upper end 'portion'of the pin extends upwardly out of the head 12, as shown;

Referring particularly toFIG. 1, the bed of a punch press, generally designated 5 24, is provided with a cylinand sfirmly lodged in openings respectively are a pair of pins 72. The lower end portion of each pin occupies the upper portion of its opening 70, and the upper end portion of the pin extends upwardly out of thehead 62, as shown.

Referring particularly to FIG. 8, bed of a punch press, generally designated 74, is provided with a cylindrical opening 76 terminating at its upper end in an axially tapered portion 78 anda cylindrical portion 79, and on diametrically opposite sides of the opening 76 respectively are. a pair of axiallyshiftable punch bars-.80 provided with beveled ends 82. Thehead of the punch press, generally designated 84, is-provided with a pair of laterally spaced depressions 86.

Injthe manufacture of the screw, the threaded shank 60 and a plain countersunk head, generally designated 88, are formed in conventional manner. Then the screw is mounted upon the bed 74 of the punch press by inserting its shank 60 intheopening 76, whereuponthe plain countersunk head 88of the screw seats in the mouth 78 of the opening 76 with its upper surface 66 flush with the surfaceof the bed 74. Now the head 84 of thepunch press is lowered through the position of FIG. 8 to that of FIG. 9, whereupon 'thepunch bars 80 are actuated thereby to punch-shear from the plain countersunk head 88 the pins 72, leaving in the head 62 the openings 70. Thelower end portions of the pins 72 remain in the openings 70' while the upper, end portions of the pins 72 are projected into'the depressions 86 in the undersurface of the head 84 of the punch press, as shown.

.-Referring particularly to FIGS. 11, 12, and 13', the tool for applying the modified screw is generally designated 90. The tool comprisesa main body 92, thelower' end of which is provided with'a cavity 94 and a pair of diametrically opposite depressions 96, and the upper end of which is provided with a handle 98.

Referring particularly to FIGS. 12, 13, and 14, the work which is to be secured together by the modified'screw comprises, for example, mutually overlying plates 100 and 102. .Thework issp-rovided with .a-tapped opening used to turn the screw tight and to drive the pins down I into the head of the screw. .Wh'en the pins are driven in,

104 terminating at its upper end inan axially tapered mouthl06; The shank 60 of the screwis threaded into the opening 104 until the head of the screw nests in the axially tapered mouth 106 of the opening 104, where-I uponrth'e lower end ,ofthe tool 90is applied to the head 62, as shown inFIG/lZ. Thehead 62 nests snugly in thecavity 94 with the upper end portions of the pins 72 Nowthe tool is turned approximately 90 to tighten the screw. The tool is then raised to disengage the pins 72 fromthe depressions 96 and turned to place the depressions 96, out of alignment with the pins 72, whereupon a harinherfis'applied to the upper end of tool 90 to drive the pins 72 back intothe head 62 of the screw, asjshown in'FIG. 13. "It will be noted that the pins 72 fully occupy the openings 70, vand referring particularly to FIG. 14, it will be observedv that the upper end'surfaces of the pins'72 are flush and-merge with theupper. surface 66 ofthe screw head 62.

Screws made in accordancewith the invention are s engagedrespectively in the depressions 96, as shown. 2

steel, for example, Vega, suitably treated drill rod or heat treatable stainless steel may be used. A mild steel of medium carbon content may be Chromized; to make a chromium carbide surface which (381111011136 penetrated except by a diamond wheel. Other metals, suchas titanium, may beused. v a

' It will be observed that one and the same tool may be the ends thereof are'flush and merge smoothly with the top surface of the screw head without requiring a grinding or any other secondary operation. Installation costs are held ,to a minimum. 'The head of the screw cannot be sawed, chiseled, or drilled-forforming a slot, groove,

or opening to receive a tool applied to remove the screw.

The screw is trulynon-removable, except bya cutting I torchor the like.

It will be understood, of course, that the present invention, asdescribed andshown, is susceptible to various changes and modifications which may be made without any departure from the general principles or real spiritof the invention. Accordingly, it is intended to claim the present invention broadly, as well asspecifically, as indicated in the appended claims.

Having thus described'my invention, I claim as follows;

1. In a non-removable screw, aunitary assembly'co m prising a threaded shank, a headformed integral with said shank and of a diameter substantially greater than the diameterof said shank, and a plurality of pins each punchsheared from the part of said head overhanging said shank, and each lodged-firmly'in a through opening.

formedin said head by said punch-shearing, with approxi mately one-third the length ofthe pin projecting up.- Wardly out of said opening, said pinbeing adapted'for being driven back into said opening and disposed with the opposte ends thereof respectively flush with the-top and bottom surfaces ofsaid head, said assembly in all its parts being made of hardened metal substantially fashioned'from hardenablesteel, andafter they are other wise fully formed, they are suitably hardened (to Rockwell reading in the order of-C-). For example, the screw may be fashioned from a low carbon SAE 1010 steel-and then case' hardened in cyanide or ammonia to get a deep .hardskin' which is impenetrable except by, v

grindingor burningwith a cutting torch. Instead, atool immune to being sawed,chiseled or drilled.

2. The screw defined in claim 1 wherein each of the pins is "uniform in transverse sectionand a pairofthe pins are disposed respectively upon opposite sides fof the.

2,462,199 Kehoe Feb.f22, 1949 

1. IN A NON-REMOVABLE SCREW, A UNITARY ASSEMBLY COMPRISING A THREADED SHANK, A HEAD FORMED INTEGRAL WITH SAID SHANK AND OF A DIAMETER SUBSTANTIALLY GREATER THAN THE DIAMETER OF SAID SHANK, AND A PLURALITY OF PINS EACH PUNCHSHEARED FROM THE PART OF SAID HEAD OVERHANGING SAID SHANK, AND EACH LODGED FIRMLY IN A THROUGH OPENING FORMED IN SAID HEAD BY SAID PUNCH-SHEARING, WITH APPROXIMATELY ONE-THIRD THE LENGTH OF THE PIN PROJECTING UPWARDLY OUT OF SAID OPENING, SAID PIN BEING ADAPTED FOR BEING DRIVEN BACK INTO SAID OPENING AND DISPOSED WITH THE OPPOSITE ENDS THEREOF RESPECTIVELY FLUSH WITH THE TOP AND BOTTOM SURFACES OF SAID HEAD, SAID ASSEMBLY IN ALL ITS PARTS BEING MADE OF HARDENED METAL SUBSTANTIALLY IMMUNE TO BEING SAWED, CHISELED OR DRILLED. 